Project Summary/Abstract Thrombosis and infection remain significant barriers to development and implementation of advanced blood- contacting medical devices. The objective of this application is to create and test novel biomaterials that combine chemical and surface texturing approaches to improve hemocompatibility. We will develop novel, Nitric Oxide (NO)-releasing polymer (PU) materials with topographies ranging in scale from 10?s of microns to 100?s of nanometers and will test these in a rabbit-catheter model and in advanced benchtop testing. The Central Hypothesis of the work states that Platelet adhesion/activation and bacterial adhesion are influenced by both surface chemical and surface physical properties. Biomaterial surfaces bearing a combination of topographic modification, polymer chemistry and active molecule release that impart resistance to platelet and bacterial adhesion will increase the efficacy of these materials in reducing platelet adhesion/activation and bacterial adhesion/biofilm formation beyond what would be expected from a single modification strategy under both in vitro and in vivo conditions. To test this hypothesis, we propose 3 specific aims that involve testing catheters in a rabbit model for periods of 7 and 28 days. These catheters will be based on our published studies showing benchtop success in reducing platelet and bacterial adhesion by implementation of sub-micron texturing with NO release. In Aim 2, we will develop more advanced texturing protocols that incorporate feature sizes ranging from 10?s of microns to 100?s of nanometers simultaneously, and will also incorporate NO release. We will also develop a novel material based on polyphosphazene chemistry that has shown promising results in benchtop testing but needs improvement to be suitable for texturing and NO release in a catheter configuration. Finally, we will carry out basic science studies on these materials in order to identify characteristics that make the materials likely to succeed in a catheter model as well as to inform the Biomaterials Community about processes involved in platelet adhesion, biofilm formation and blood coagulation in general. The successful completion of this application will provide a novel approach to improve the biocompatibility of current biomaterials, improve patient care and incur cost savings.